Projeto Observacional para 2015B - SO2015B-004

Autor: Alvaro Alvarez Candal
Instituição: ON
e-mail: alvarez@on.br

Co-autores:
Jose Luiz Ortiz
Noemi Pinila Alonso
Rene Duffard
Daniela Lazzaro
C. Ayala Loera

Título: Visible photometry of "odd" trans-Neptunian objects

Resumo: During a recent survey made by our team, aimed at measuring absolute magnitudes of a sample of trans-Neptunian objects, we have detected some objects with an odd photometric behaviour. The absolute magnitudes are measured using phase curves that show the change of the magnitude with the phase angles (angle on the body that subtends the separition Sun-Earth). The usual tendency is for objects to become brighter with decreasing phase angle due to a combined effect of shadow-hiding and coherent backscatter. Neveretheless, we have detected a few objects that show the opposite behaviour, i.e., they become fainter with decreasing phase angle (negative slope). These negative slopes of the phase curves could arise due to different phenomema: radical changes in surface characteristics (for example cometary activity or collisions), binarity or satellites, or more complex systems such as rings. We propose to observe a sample of objects with negative slope of the phase curve, and with few datapoints, aiming at explaining these curves and constraining its possible causes.